ABSTRACT
In a real-time digital control system, it takes time to implement data acquisition from sensors and signal processing to calculate and generate control commands. Both of them lead to time delay in the feedback control system and are, respectively, called signal measurement time delay and controller computing time delay. To implement the digital control system, sampling rate must be selected carefully and should be determined by not only satisfying the conditions of Shannon’s sampling theorem [1] but also making the desired performance achievable. A higher sampling rate is generally preferred since it implies improved performance and better vibration rejection capability. However, increasing the sampling rate will make the time delay affect the control system performance more significantly. The time delay is usually smaller than the sampling interval in the digital control system. A longer time delay will have more severe impact on the control system performance.
